1Department of Medical Pathology, Ege University Faculty of Medicine, İZMİR, TURKEY2Department of Radiology, Ege University Faculty of Medicine, İZMİR, TURKEY3Department of Orthopedics and Travmatology, Ege University Faculty of Medicine, İZMİR, TURKEY

Objective: Bone cysts are benign lesions occurring in any bone,
regardless of age. They are often asymptomatic but may cause pain,
swelling, fractures, and local recurrence and may be confused with
other bone lesions.

Results: Aneurysmal bone cyst, solitary bone cysts and mixed cysts
were frequently seen in the first two decades of life while the others
occurred after the fourth decade. Aneurysmal bone cysts, intraosseous
ganglion and pseudocysts were more common in women contrary to
solitary bone cyst and mixed cysts (the female/male ratio was 1.22,
2 and 1.5 versus 0.7 and 0.5, respectively). Aneurysmal bone cyst,
solitary bone cysts and “mixed” cysts were mostly seen in long bones,
predominantly the femur, while epidermoid, hydatid and pseudocysts
were all seen in flat bones like the vertebra, pelvis and mandible
(p=0.001, chi-square). Repeat biopsies were performed in 19 cases
(13.3%), 84.2% of which were aneurysmal bone cyst (5 conventional,
9 solid, 1 secondary and 1 subperiosteal) and three (15.8%) were
mixed cysts (p=0.02, chi-square). Notably, some of them were located
in inaccessible areas of pelvis (n=3), femur (n=3) and maxilla (n=2).

Conclusion: The most common and challenging intraosseous cysts
are aneurysmal bone cysts, particularly the “solid” variant. The
“mixed” aneurysmal-solitary bone cyst “subgroup” requires further
research with larger series to be defined more thoroughly.